Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Show Questions - May 10, 2012
1. A viewer from Wyoming has been told about verbenone pouches for controlling pine bark beetles. They haven't seen them on their spruces, but they are on trees about a mile from their home. They're wondering if these pouches will work.
a. I'm not aware of what that is, but if it's a mountain pine beetle product and you have spruce trees that you're worried about, there's no need to worry. The mountain pine beetles will leave the spruce species alone, and there is nothing to worry about. They might go to Extension if they have other concerns.
2. This is a viewer who wonders about something that we recommended which was a split application of a pre-emergent herbicide and grub control going down mid-May. They wonder how to avoid over-fertilizing their lawn.
a. With most of the weed-control products, a lot of those are impregnated in fertilizers, but you should be able to purchase those by themselves and not on fertilizer. So just select the right product that doesn't have a fertilizer and you shouldn't have any problems with over-fertilization. Read the label or ask somebody.
3. We have had a lot of questions about this: about mushrooms coming up where tree stumps were and what to do about that.
a. With those mushrooms coming up, that means the tree roots are decaying down, which is what we want. There is nothing to do for suppression. You can mow them off, but they will continue to pop up as long as the roots are decaying down in the ground. That means you have a great source of nitrogen for your turf or ornamental plants. It's a temporary problem. It will go away with time.
4. This is a viewer that actually watches our show from podcast on Friday from Evanston, Illinois. 'Anabelle' hydrangeas are on the north side of the building, they've done beautifully, but this year leaves were yellow, spotty, blackened--worse on the taller stems--but new shoots seem normal. They have had a very mild winter and the warmest March in 142 years, but they also a light frost, and I know you have a lot of 'Anabelles' on campus.
a. Sounds like they were nipped a little bit, so I would just remove those stems, cut them back, and new growth will fill in.
5. This is a viewer in Burlington, New Jersey. They have a wooden shed next to their home that is a beacon for carpenter bees in the spring. He doesn't want to harm them, but they dive bomb the children and buzz. He doesn't want them in the house.
a. I assume he doesn't mean just accidently getting in through an open door, but actually burrowing in. They're not going to go through painted or finished wood, so if you keep your house in good order, keep it painted, that will make a difference. If it's siding, it shouldn't be an issue. If it's brick, there shouldn't be a problem unless there is mortar decaying that they can get in there.
6. This is the viewer from Lincoln who wants to know how to get nutsedge out of an asparagus bed without harming the asparagus, and they don't want to dig because they're afraid it will damage any new shoots that are coming back up
a. Unfortunately, I don't believe there is a way to take yellow nutsedge out of asparagus post-emergence. I think the viewer is limited to hand-pulling at this point in time. Next year, there will be nutsedge again. He may think about a pre-emergent application prior to the asparagus and nutsedge coming up next year, but post emergence, I think they're kind of out of luck.
7. This is from a Columbus viewer. It's a cherry, yielded beautifully, but last spring it appeared to develop a rot, the fruit withered away, they removed all of it. This year it's turning brown again already, they've sprayed with a copper sulfate, but they don't know what's going on and whether they are, in fact, going to get fruit.
a. This one had me stumped a little bit. I had to do some research. This appears to be botrytis or green fruit rot. Brown rot doesn't typically affect fruit of this age. Botrytis or green fruit rot affects wherever the petals are able to touch the fruit. That's why you're seeing it at the top of the cherry where it's attached to the stem, and it's most active when we get a rain event when we have blossoms. You'll have to do a fungicide application when it's still in the blossom stage. If you were trying to treat for brown rot, you most likely used the copper sulfate a little too late. With green fruit rot, the fruit will fall off the tree; if it's brown rot, it has a tendency to hang on the tree itself. That's one difference between the two of them. That would be my suggestion, maybe you'll get some fruit off of it this year. If not, apply a fungicide on in the spring, when it's blossoming.
8. A viewer from Arapahoe: she is new to gardening with sweet potatoes, wonders whether they should be planted in rows, how deep, should the runners be allowed to root.
a. They're a viney crop. They require a bit of room. If you're going to have multiple rows, you're going to want them four or five feet apart, you'll want a ridge, unlike regular potatoes where you create a ditch, you ridge these, so a little higher ridge, and a furrow between the rows. When planting them, put them in there, plant them three or four inches deep, and I wouldn't worry about the rooting so much, you want to keep the plants fairly far apart, maybe 18" apart, and then the big thing is with sweet potatoes is not damaging the plants themselves. You can do your weeding and that sort of thing, but we don't want to get into the plants too much. They'll fill those ridges with roots and we don't want to damage them at all, so we don't want to get carried away with that.
I know a lot of people are interested in growing their own sweet potatoes.
9. We have four more moth questions, so I'm going to let you answer, once and for all, the miller question. They have miller moths. What to do?
a. The miller moth, yes, they get indoors, in garages, in your windows, all over the place. The things to do to limit that: don't keep the porch lights on at night, close curtains at night, so you don't have as much light coming through your windows. That will help. Now, when they all try to find a place to hide for the day, then you've got to make sure all of your windows are well sealed, which might be tough in an old farmhouse. You also have to make sure all your weather stripping is in good condition, and there are no gaps. I've had lots of questions myself about this, any type of screened-in porch, make sure you have all the seams caulked, make sure the weather stripping is good, and this is a matter of patience. I can break out the standard entomologist's line here and say "patience, grasshopper" and let it go at that, hopefully they will fly off west.
10. This is a windmill grass question. But, also a barley question. This viewer has windmill grass and little barley coming up in their yard in Furnas County, and it’s in a bluegrass/buffalograss combination, and they want to know how to control this.
a. There's not a single solution to that, the reason being little barley is a winter annual, it germinates and comes up in the fall, it's producing seed right now, and it will be done and gone here probably in the next three or four weeks, probably. We talked about tumble windmill grass earlier in the show. It is a perennial, and it will hang on throughout the summer, here.
So for control of the little barley, we need to look at a fall application of a grass pre-emergent type of product, probably the same thing that works for large crabgrass is probably going to work for pre-emergence for little barley. When I talked about the windmill grass, a post emergence application of Tenacity or high amounts of glyphosate or a Roundup product spot treated on the tumble windmill grass.
11. When to treat for brown patch or summer patch? They want to know what time they would expect to see it and then when they put down what product?
a. Summer patch: that one gets a treatment that goes on, typically, about right now. We haven't discussed whether to bump up that timing this year. Typically, with summer patch, just overseed with a resistant variety/cultivar this fall, that's the best way. It's hard to get those roots back healthy and established to be able to handle the drier weather during the summer months. So over-seeding in the fall is the best thing to do, and there are great resistant varieties.
For brown patch, usually we start looking at it starting to show up in about the middle of June. Typically we don't recommend any preventative application. We'll do fungicide when we see it. If you put down too much fertilizer, that will cause brown patch. It's like the question we had at the beginning of the show: if you're trying to put on pre-emergent and grub control, make sure it doesn't have nitrogen in it, because you'll be setting yourself up for brown patch in the next couple of weeks.
12. This viewer was driving around in Ralston and they saw this gorgeous tree in bloom, they have no idea what it is, and I think we also have a close-up picture that shows our viewers how beautiful the flowers are. They want to know what it is.
a. Well, that's 'Purple Robe' black locust, so it's a hybrid. It should have a little thorn to it, not too nasty, but black locust has a little bit of a thorn to it. This tree doesn't look too old, and they will grow fairly quickly, so they're not a slow-growing tree at all, and occasionally one of the issues with the ones we have on campus is that they have a tendency to sucker a little bit. If you get one, you might get two or three, which isn't all bad if you like them. I know there used to be a few around, but I don't recall whether they smell as wonderful as regular old black locust does. That would be one of the things that would make it even more beautiful.
13. A Grand Island viewer wants to know about ticks-- do they ever spin a web, like a spider? They said they were in the woods and flicked one off, but it swung right back around and landed again.
a. Ticks do not produce silk like spiders do. What may be going on, maybe they were caught on a piece of spider silk. I've been running into a lot of spider webs around, so that could be part of it, or it could have just been a small, thin thread from clothing it can been caught on and just happened to be caught enough that when you flicked it off, it was able to come back around.
14. This is a poison ivy question. A viewer has some behind their shed. They don't want their children to get into it. Any suggestions on getting rid of poison ivy?
a. Poison ivy -- you can do a couple things. You can use a brush killer that has triclopyr and Roundup in it. Use a rubber glove inside of a cotton glove, and then brush the leaves. Or you can do a cut-stump treatment where you find the base of the plant, cut it off at the base and then use a brush to put something like Tordon right on the stump of that poison ivy. Just wear gloves and be careful around it. Don't burn the foliage of the poison ivy that you have cut off. If they're really concerned about that, they'll need to have a professional come in and do it.
15. These are peach questions. The first is, they have actually apricots and peaches. They have three apricots that bloomed this spring and then the flowers on one of the trees turned brown--no fruit (the other two have fruit). They wonder what is going on. Tthey also have peaches and apples that are three to four years old, they also bloomed, and they're not setting fruit, and this is in Tobias. And another viewer says the peaches off their peach tree don't taste good. There is an ornamental peach next to it.
a. The one with some brown blossoms could be brown rot on the apricot tree. Brown rot will affect the blossoms, or we could have botrytis blight moving in. The other thing I would look at is where your apricots are planted. If that one was maybe a little lower and you were dealing with the problems with the apples. The one that had blossoms and then no fruit, could have been a late frost. We got cool weather, with blossoms on, it's very possible it's just frost damage. If it's three or four trees, one is a little bit lower, and could get more frost injury. It wasn't a really good year for fruit trees because of how early they bloomed, and we were still in that heavy frost period.
The peach not tasting good -- I've had a similar experience. Last year, I had a peach and apricot tree, it seemed like they were all done, and then we had a couple of cold nights and I didn't see any apricots. Last year my apricots were a little watery, I had a bunch of them, but they weren't what I expected like I've had in the past. It's hard to say. I think that in our soils here, they may be a little heavy for apricots and peaches, sometimes people have good luck with them if they're sited right. But sometimes not. If it gets too hot too fast when they're setting, that can that affect the flavor. That's why Colorado is the peach capitol. Keeps the temperatures down a little bit
16. This is a Laurel, Nebraska, question. They have an American Linden that sends up a lot of suckers. She used Sucker Stopper but she wants to use Roundup on the suckers. Good idea?
a. No, I would stay away from it. I was looking at some trees on campus that have a tendency to do that. There are crabs that can be beautiful, and lindens are another one. Once they start suckering, they don't stop. You just have to be tenacious with it. I've had pretty good luck with linden if you let two or three of the suckers grow, and then they stop, but then you have a multi-stem.
17. This is a viewer that has 3-year-old hybrid poplars where the leaf grows out of the branch. So probably right at the petiole they have this bulbous growth, and when they break it open it has bluish-green mites and eggs in it. This is in Union, Nebraska.
a. This is something I’ve actually run into before. It's not mites, it's aphids. What happens with these, the aphids come back in the fall, they lay the eggs on the buds, and they hatch right after the leaf emerges from bud dormancy in the spring. They start feeding on that leaf petiole and it forms a gall around the aphids. And so what you’re thinking are eggs in there are actually real small nymph aphids in there. The larger ones are getting to adults. If you catch it at the right time you’ll even find winged ones in there. This species is variable. They’re in the genus Pemphigus. One of the important aphid species of this is the sugar beet root aphids and they are what people in the western part of the state would probably identify with that a little more. They're not going to hurt your poplar trees.
18. You get two pictures together. The reason being, they're both in the same genus. The first viewer wants to kill it and the second viewer wants to keep it. The first one is this plant in the lawn. They want to know what is it and how to get rid of it.
a. That is wild violets. It’s a very common lawn weed. It’s difficult to control. It’s a perennial. The best way to control it is an integrated herbicide program, something with the active ingredient Triclopyr in it, and just be persistent about applications on wild violets.
19. And the second one, a viewer sort of lost track of this plant, and they want it, they love it, and they want to know where they can get it.
a. Yes, I think I read in the description this is around an excavated basement area. This is, I think, the common name is "Johnny jump ups". The scientific name is Viola tricolor. You see the three colors on the petal. It's a winter annual and when they maybe moved some soil out of there, it's entirely possible they moved all the seed out of there as well. So if they just let these plants go to seed this year and build up the weed seed bank, they'll have Johnny jump-ups for many years to come. And that's actually a Lawrence, Kansas, viewer. And I do know some nurseries actually sell Johnny jump-ups as plants. So maybe there's somebody in that area that can get them one.
20. This is a viewer in North Bend that has apples that are fruiting for the first time. They're wondering what they should spray to keep insects and diseases off. Or, is it too late?
a. With flowering fruit--apples, cherries, anything like that--we really recommend following a spray program, a fungicide and insecticide spray program, to keep the rots and spots and critters out of your apples. You can find most of that on-line. Michigan State has a great tree fruit spray schedule. It tells you approximately at this flowering stage you apply this one and then this one and so on throughout the year, just to protect the fruit all season long.
21. This is a Gothenburg viewer. They have three different vines--silver lace vine, clematis, and honeysuckle. She wants to know whether they need to be cut to the ground in the fall. She's a little confused on the new wood/ old wood thing, and hers have a lot of dead in them. She wonders what to do about them.
a. The silver lace, that's one that you will want to take to the ground, or within a foot or so. I hate to cut things too close to the ground. The honeysuckle is one you don't want to take to the ground, but you want to go in clean it up a little bit. There will be some dead vines in there, so you're going to want to do some cleanup in there. And as well with the clematis, I don't like to go in and take it too far back. You can get aggressive with them, but I think you're better off to go in and clean up the dead and clean up the base of the plant. Don't cut too much on anything other than all the dead.
22. This is a viewer who lives in Omaha. They say when they walk through the backyard, there's about a zillion, gazillion, trillion little white gnats. They wonder what they are and how to get rid of them
a. We've been hearing a lot of reports of high leaf-hopper populations. And if this is in the grass, likely this is what we're seeing. This is probably due to our really mild winter this year. And that's just the way it is, unfortunately.
23. This is a Cedar County viewer who has leafy spurge. When to treat it, and with what?
a. Right now is a good time to treat it. Just a little background: leafy spurge is a noxious weed in the state of Nebraska. Folks that do have leafy spurge on their property need to make an effort to control it. Right now using Tordon applied here in the spring is a way to suppress it. But because it's a perennial, it's going to take probably multiple applications over a couple of years to really knock those patches back. If they have it in a pasture or something like that, a product like Tordon or Grazon P+D is probably what they need to use. I'm glad you mentioned the noxious status on that one.
24. This is a viewer that has a couple of 15-foot Colorado Blue Spruce. The top three feet have turned brown. Lower portion appears healthy. They've been told it's caused by a borer. Any notion on whether that might perhaps be a canker or environmental or something instead?
a. I would probably look for a canker development. Any sunken area in that upper part of the canopy that's preventing any water or nutrient movement can really be detrimental to a Colorado Blue Spruce and make it die out. There isn't much you can do about it. There’s not much for borers in Blue Spruce. Really the only thing I see that will get it down as far as an insect is pine needle scale when that gets really bad.
25. We have a couple of hosta questions. The first is from a viewer who has new hostas that they bought from a nursery about five weeks ago. No new growth. Is that normal?
a. I don’t think that’s unusual. I would look at what you planted them in and what the soil was like. We talked about adding compost and adding things to our soils to improve their fertility. So if you didn't do that, you can still do that. I would go in and gently work around the plants and add some topsoil, some compost, and that sort of thing.
26. This person has hostas burning on the south side of the house.
a. They shouldn't have been planted on the south side of the house.
27. Any ideas for what they ought to plant?
a. There’s a lot of our native perennials that can be planted there. You can move those hostas. If you can keep them alive and they’re something you want to use, you can move them in August. I've had good luck with August moves with hosta.
28. We have a viewer who sent us pictures of a really bad trunk rot on viburnums. Any idea on viburnum borer sorts of issues?
a. It might be more of a canker. There are a few fungal things that will go after the viburnum if there was an injury there. There isn’t a lot you can do. Prune out as much as possible. There may be borers. I would want to take all the dead out. If you have an insect problem, you'll remove that, as well. I think the viewer said they have 200 feet of American Cranberrybush, so the chance of those getting borers are good.
1. Is it possible for this viewer to add anything to the soil to produce good tomatoes when he's not rotating them and he's only getting three hours of sun a day?
a. The sunlight is the problem. Certainly you can add new compost, new topsoil each year, kind of double-dig the garden—all those things to help your soil, but if it's in the shade of a tree, we need to prune the tree, or we need to move the garden.
2. What is the most common fern that we see used in the eastern part of the state?
a. The most common fern? I don't know. [Cinnamon]
3. How do you kill Euonymus fortunei, the purpleleaf or the wintercreeper?
a. I would want to prune it back, to the crown to the plant. Either dig it out, which would be tough. We could use a Roundup. And you might want to even think of using something like Trimec, but I think you would be able to weed it out, and pull it out. Just be persistent. That's what I would do.
4. Yellow-green foliage on a new baldcypress in Fremont.
a. It’s kind of showing some clorosis and I see that on ours sometimes. I would be patient. You might want to have a soil test to see if you have very, very basic soil and see if you can do something with that.
1. This is a viewer who has a fungus, they think, on the leaves of their ash trees, both 'Autumn Purple' and green, in the St. Paul area. Should they spray for something, or what is going on with ash?
a. Typically with ash, we see ash rust if it's orange. There is nothing you can spray now. Otherwise, we see anthracnose later on in the year. Typically we don't recommend a fungicide application for that.
2. This is a viewer in North Platte who has a silvery fungus in their Kentucky bluegrass almost every summer. They’ve had it treated but they want to know what it might be and what product they might use.
a. It could be powdery mildew if they touch it and it wipes off really easily. There isn’t a lot of fungicide you can use. It's pretty persistent. If it’s too shaded, increase air circulation and light.
3. This viewer has a 10-year-old cottonwood that all of a sudden has become sparse and droopy, no good leaves anymore. It’s really going downhill.
a. Most likely it’s a root issue. Time to consider replacing it. That could be cottonwood borer. They tend to hit the younger trees and that’s why we see full mature cottonwoods. You don’t see the suckers very often or they don’t last very long. Because the cottonwood borer usually gets them. The other thing I wonder is if they actually bought a cottonwood. I think the only one that is widely available is 'Siouxland' and that’s not a very good cultivar. For the first 20 years they are spectacular and then the next three that it goes pretty fast. Pretty hard to say if it’s a canker or if it’s a borer.
4. This is a viewer who had a healthy ash that rotted off about 12 inches above the ground. Any sort of pathogen that would cause a tree to rot?
a. Most likely there’s was an injury there and a canker moved in and rotted it out. You're better off removing the tree and replacing it, also.
1. How do you kill annual bluegrass, Poa annua, in bluegrass?
a. There's not a good selective way to take that out. There are some professional products, but for the homeowner, it's very difficult to get it out. The better thing to do is to encourage the Kentucky blue.
2. How do you get brome out of a lawn and out of a rhubarb patch?
a. While the rhubarb is not in season or doesn't have foliage on it, you can use Roundup on the brome. It's very difficult to get brome selectively out of a bluegrass lawn.
3. Is there an herbicide you can put on ground in a sandy lakeside area that would not hurt either the aquatics or the wildlife?
a. Yes, there are herbicides such as Roundup or glyphosate or 2,4-D that do have aquatic labels, and you can control a number of weeds with those.
4. Is Tenacity or sulphentrazone best for controlling nutsedge in bluegrass?
a. Sulphentrazome. With Tenacity, you'll see some bleaching or the whitening, but long term, sulphentrazone is much more effective on yellow nutsedge.
1. We have a viewer who has pinholes and curling leaves in their pin oaks. Any ideas on pinholes in pin oaks?
a. Might be canker worm getting started. I don't remember the treatment for those.
2. How do you control those icky green worms in broccoli.
a. Encourage your wasp population. That’s one way to do it. They will hunt them down. Or if you don’t like having your wasp population up, usually anything with carbaryl will do a good job of cutting them back.
3. Does it make sense to order lady bugs and lacewings and release them as beneficials in a landscape?
a. Only if you don't order the adults. The adults tend to fly, especially with the lady beetles.
4. Something is defoliating lindens, the big giant ones, in the Fotenelle Forest area. Any ideas on that?
a. There's a number of caterpillars that will get into lindens, but there’s nothing that really has a good knack of defoliating lindens. This might be a picture opportunity for that viewer.